EP0182535B1 - Thrust bearings - Google Patents
Thrust bearings Download PDFInfo
- Publication number
- EP0182535B1 EP0182535B1 EP19850308023 EP85308023A EP0182535B1 EP 0182535 B1 EP0182535 B1 EP 0182535B1 EP 19850308023 EP19850308023 EP 19850308023 EP 85308023 A EP85308023 A EP 85308023A EP 0182535 B1 EP0182535 B1 EP 0182535B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ridges
- thrust
- bearing
- disk
- thrust bearing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/04—Sliding-contact bearings for exclusively rotary movement for axial load only
- F16C17/042—Sliding-contact bearings for exclusively rotary movement for axial load only with flexible leaves to create hydrodynamic wedge, e.g. axial foil bearings
Definitions
- Fluid bearings are now being utilized in an increasing number of diverse applications, These fluid bearings generally comprise two relatively movable elements with a predetermined spacing therebetween filled with a fluid such as air, which, under dynamic conditions, forms a supporting wedge sufficient to prevent contact between the two relatively movable elements.
- foils in the space between the relatively movable bearing elements.
- Such foils which are generally thin sheets of a compliant material, are deflected by the hydrodynamic film forces between adjacent bearing surfaces and the foils thus enhance the hydrodynamic characteristics of the fluid bearings and also provide improved operation under extreme load conditions when normal bearing failure might otherwise occur. Additionally, these foils provide the added advantage of accommodating eccentricity of the relatively movable elements and further provide a cushioning and dampening effect.
- a fluid thrust bearing comprising a pair of members arranged for relative rotation with respect to one another, one of said pair of members being adapted rotatably to support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted on one of said pair of relatively rotatable members, said compliant foil bearing comprising a thrust disk having a plurality of compliant foils and an underspring including a plurality of upper ridges and lower ridges alternately disposed thereon, characterised in that the upper ridges have a height which is greater than the height of the lower ridges.
- the pair of members comprise a thrust runner, and a thrust plate rotatably supporting the thrust runner, the compliant foil bearing being mounted on the thrust plate with the compliant foils disposed towards the thrust runner.
- the upper ridges have a height generally between 0.00254 cm and 0.0254 cm greater than the height of the lower ridges.
- the compliant foils may be individually mounted on or integral with the thrust disk.
- the upper ridges outwardly diverge radially
- the lower ridges outwardly diverge radially
- the space between adjacent lower ridges outwardly converge radially.
- the invention also extends to an underspring per se as described above in accordance with the invention.
- Figure 1 illustrates a thrust runner 10 including shaft 12, the runner 10 being rotatably supported on a thrust plate 28 by means of a thrust bearing disk 14 and a thrust bearing stiffener or underspring 22.
- the thrust bearing disk 14 has a plurality of bearing pads or foils 16 mounted thereon, while the thrust bearing underspring 22 includes a plurality of upper ridges 24 and lower ridges 26 alternately disposed thereon to provide stiffness for the thrust bearing disk 14.
- the thrust bearing underspring 22 generally comprises a thin compliant ring ranging in thickness t d between 0.00254 cm and 0.508 cm and can be produced by conventional chemical etching techniques.
- the upper ridges of this thrust bearing underspring 22 have a height defined as t i .
- the upper ridges 24 diverge radially outwardly in width as best illustrated in Figure 2.
- the width of these upper ridges 24 is generally defined by W 1 with the width at the outer periphery defined as W o ( Figure 2) and the width at the inner periphery defined as W, ( Figure 2).
- the outer periphery width W o is generally from 0 to 30% greater than the inner periphery width W,.
- the upper ridges 24 are laterally defined by radially emanating lines.
- Certain of the upper ridges 24 may include outer projections 25 having cutouts 29 which can be utilized to maintain the position of the underspring 22 with respect to the thrust plate 28. As shown in Figure 1, similar projections 27 may be spaced around the thrust bearing disk 14.
- the upper ridges 24 may also include inner projections 23 which extend radially inward of the inner periphery of the central aperture of the underspring 22.
- the lower ridges 26 include struck-out springlike tabs 34 extending toward the thrust plate 28. These tabs 34 may be provided near the outer periphery of the lower ridges 26, or near the inner periphery of the lower ridges 26, or alternating between these two positions as shown in Figure 2.
- the tabs 34 provide the initial pre-load for the bearing assembly to maintain static contact between the thrust plate 28, the stiffener or underspring 22, the thrust disk 24, and the thrust runner 10.
- These relatively soft tabs 34 readily deform under hydrodynamic pressure such that the lower ridges 26 will contact the thrust plate 28 as illustrated most clearly in Figure 6.
- the height of the lower ridges 26 is defined as t 2 with their width generally defined as W 2 .
- the lower ridges 26 also diverge outwardly radially with the width at the inner periphery defined as W a ( Figure 4) and the width at the outer periphery defined as W b .
- the outward divergence of the lower ridges 26 is considerably greater than the radial outward divergence of the upper ridges 24.
- the lateral edges of the lower ridges 26 are defined by a pair of non-radial lines which intersect much closer to the inner periphery of the underspring than the centre point of the underspring. The spacing between the upper ridges 24 and the lower ridges 26 thus outwardly converges as shown by a comparison of Figures 3 and 4.
- the dimension for the height t 1 of the upper ridges 24 will always be greater than the dimension for the height t 2 of the lower ridges 26. While the relationship between t 1 and t 2 may vary considerably, depending upon different operating conditions, t 1 will generally be greater than t 2 by between 0.00254 cm to 0.0254 cm in order to accommodate deflection of the thrust disk due to hydrodynamic pressure.
- the resiliency or spring rate of the underspring 22 can be varied by changing its thickness or the dimensions of the upper and lower ridges 24, 26.
- the space between adjacent lower ridges 26, defined as W 3 in Figure-3, has a marked effect on the stiffness and will generally outwardly converge at least slightly in order better to accommodate the hydrodynamic pressure forces which increase radially.
- slots 30, 32 can be provided transversely across the upper ridges 24 to divide the upper ridges into three separate sections. With the radially diverging upper ridges 24 divided into three separate sections, the stiffness of the upper ridges will more closely conform to the radially increasing hydrodynamic pressure forces.
- the foil thrust bearing of the present invention is shown further enlarged in Figure 5 (static condition) and Figure 6 (dynamic condition).
- Figure 5 static condition
- Figure 6 dynamic condition
- the size of the underspring 22 has been enlarged considerably, more particularly in the axial direction, than the thrust bearing disk 14. It is important, however, to stress the relative position of the disk 14 and its foils 16 with respect to the upper and lower ridges 24, 26 respectively of the underspring 22 and in particular the interaction therebetween in the dynamic condition of Figure 6.
- the foils 16 of the thrust bearing disk 14 are shown as having the upper ridges 24 of the underspring 22 generally under the trailing edge half thereof. In this static condition neither the disk 14 nor the underspring 22 will be deflected and both will be substantially transverse to the eventual axis of rotation.
- the arrow provided on the thrust runner 10 indicates the direction of rotational movement that the runner will take with respect to the foils 16 on the disk 14.
- the foils 16 may be curved as shown in Figure 5 or the leading edge of the foils may be tapered to a thinner thickness than the rest of the foil.
- the underspring 22 beneath the upper ridges 24 will be deflected towards the thrust plate 28 a distance defined as d 2 , such that the spacing between the disk 22 and the thrust plate 28 in this region will be less than the height of the lower ridges t 2 .
- This spacing, t 2 -d 2 depends on the bearing stiffness and hydrodynamic film pressure.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Support Of The Bearing (AREA)
- Sliding-Contact Bearings (AREA)
Description
- Process fluid or gas bearings are now being utilized in an increasing number of diverse applications, These fluid bearings generally comprise two relatively movable elements with a predetermined spacing therebetween filled with a fluid such as air, which, under dynamic conditions, forms a supporting wedge sufficient to prevent contact between the two relatively movable elements.
- More recently, improved fluid bearings, particularly gas bearings of the hydrodynamic type, have been developed by providing foils in the space between the relatively movable bearing elements. Such foils, which are generally thin sheets of a compliant material, are deflected by the hydrodynamic film forces between adjacent bearing surfaces and the foils thus enhance the hydrodynamic characteristics of the fluid bearings and also provide improved operation under extreme load conditions when normal bearing failure might otherwise occur. Additionally, these foils provide the added advantage of accommodating eccentricity of the relatively movable elements and further provide a cushioning and dampening effect.
- The ready availability of relatively clean process fluid or ambient atmosphere as the bearing fluid makes these hydrodynamic, fluid-film-lubricated, bearings particularly attractive for high speed rotating machinery. While in many cases the hydrodynamic or self-acting fluid bearings provide sufficient load bearing capacity solely from the pressure generated in the fluid film by the relative motion of the two converging surfaces, it is sometimes necessary externally to pressurize the fluid between the bearing surfaces to increase the load carrying capability. While these externally pressurized or hydrostatic fluid bearings do increase the load carrying capacity, they do introduce the requirement for an external source of clean fluid under pressure.
- In order properly to position the compliant foils between the relatively movable bearing elements, a number of mounting means have been devised. In thrust bearings, it is conventional practice to mount a plurality of individually spaced foils on a foil bearing disk such as by spot welds and position the foil bearing disk on one of the bearing elements as exemplified in U.S. Patent No. 3,635,534.
- To establish stability of the foils in most of these mounting means, a substantial pre-load is required on the foil. That 1s, the individual foils must be loaded against the relatively movable bearing element opposed to the bearing element upon which the foils are mounted. It has been conventional to provide separate compliant stiffener elements or undersprings beneath the foils to supply this required preload as exemplified in U.S. Patent Nos. 3,893,733 and 4,153,315. Under extremely high load, however, the compliance of these underfoils may be exceeded and the undersprings 'bottom out', thus destroying the load carrying capability of the bearing.
- It is an object of the present invention to provide a fluid thrust bearing with a series of compliant foils and an underspring in which the risk of the underspring "bottoming out" is greatly reduced or even avoided.
- According to one aspect of the present invention there is provided a fluid thrust bearing comprising a pair of members arranged for relative rotation with respect to one another, one of said pair of members being adapted rotatably to support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted on one of said pair of relatively rotatable members, said compliant foil bearing comprising a thrust disk having a plurality of compliant foils and an underspring including a plurality of upper ridges and lower ridges alternately disposed thereon, characterised in that the upper ridges have a height which is greater than the height of the lower ridges.
- Preferably, the pair of members comprise a thrust runner, and a thrust plate rotatably supporting the thrust runner, the compliant foil bearing being mounted on the thrust plate with the compliant foils disposed towards the thrust runner. Preferably, the upper ridges have a height generally between 0.00254 cm and 0.0254 cm greater than the height of the lower ridges.
- The compliant foils may be individually mounted on or integral with the thrust disk. Preferably, the upper ridges outwardly diverge radially, the lower ridges outwardly diverge radially, and the space between adjacent lower ridges outwardly converge radially.
- The invention also extends to an underspring per se as described above in accordance with the invention.
- The invention may be carried into practice in various ways, but one specific embodiment will now be described, by way of example with reference to the accompanying drawings, in which:-
- Figure 1 is an exploded perspective view of a foil thrust bearing according to the present invention;
- Figure 2 is an enlarged top plan view of the thrust bearing underspring of the foil thrust bearing of Figure 1;
- Figure 3 is a side elevation of the thrust bearing underspring of Figure 2 taken along line 3-3 thereof;
- Figure 4 is an enlarged under plan view of the thrust bearing underspring of Figure 2;
- Figure 5 is an enlarged sectional view of the foil thrust bearing of Figure 1 in a static condition; and
- Figure 6 is an enlarged sectional view of the foil thrust bearing of Figure 1 in a dynamic condition.
- Figure 1 illustrates a
thrust runner 10 includingshaft 12, therunner 10 being rotatably supported on athrust plate 28 by means of a thrust bearingdisk 14 and a thrust bearing stiffener orunderspring 22. The thrust bearingdisk 14 has a plurality of bearing pads orfoils 16 mounted thereon, while thethrust bearing underspring 22 includes a plurality ofupper ridges 24 andlower ridges 26 alternately disposed thereon to provide stiffness for the thrust bearingdisk 14. - As more fully shown in Figures 2-4, the
thrust bearing underspring 22 generally comprises a thin compliant ring ranging in thickness td between 0.00254 cm and 0.508 cm and can be produced by conventional chemical etching techniques. The upper ridges of thisthrust bearing underspring 22 have a height defined as ti. Theupper ridges 24 diverge radially outwardly in width as best illustrated in Figure 2. The width of theseupper ridges 24 is generally defined by W1 with the width at the outer periphery defined as Wo (Figure 2) and the width at the inner periphery defined as W, (Figure 2). The outer periphery width Wo is generally from 0 to 30% greater than the inner periphery width W,. In theunderspring 22 illustrated in Figure 2, theupper ridges 24 are laterally defined by radially emanating lines. - Certain of the
upper ridges 24 may includeouter projections 25 havingcutouts 29 which can be utilized to maintain the position of theunderspring 22 with respect to thethrust plate 28. As shown in Figure 1, similar projections 27 may be spaced around the thrust bearingdisk 14. Theupper ridges 24 may also includeinner projections 23 which extend radially inward of the inner periphery of the central aperture of theunderspring 22. - The
lower ridges 26 include struck-outspringlike tabs 34 extending toward thethrust plate 28. Thesetabs 34 may be provided near the outer periphery of thelower ridges 26, or near the inner periphery of thelower ridges 26, or alternating between these two positions as shown in Figure 2. Thetabs 34 provide the initial pre-load for the bearing assembly to maintain static contact between thethrust plate 28, the stiffener orunderspring 22, thethrust disk 24, and thethrust runner 10. These relativelysoft tabs 34 readily deform under hydrodynamic pressure such that thelower ridges 26 will contact thethrust plate 28 as illustrated most clearly in Figure 6. - As shown in Figure 3, the height of the
lower ridges 26 is defined as t2 with their width generally defined as W2. Thelower ridges 26 also diverge outwardly radially with the width at the inner periphery defined as Wa (Figure 4) and the width at the outer periphery defined as Wb. As is best illustrated in Figure 4, the outward divergence of thelower ridges 26 is considerably greater than the radial outward divergence of theupper ridges 24. Thus the lateral edges of thelower ridges 26 are defined by a pair of non-radial lines which intersect much closer to the inner periphery of the underspring than the centre point of the underspring. The spacing between theupper ridges 24 and thelower ridges 26 thus outwardly converges as shown by a comparison of Figures 3 and 4. - The dimension for the height t1 of the
upper ridges 24 will always be greater than the dimension for the height t2 of thelower ridges 26. While the relationship between t1 and t2 may vary considerably, depending upon different operating conditions, t1 will generally be greater than t2 by between 0.00254 cm to 0.0254 cm in order to accommodate deflection of the thrust disk due to hydrodynamic pressure. - The resiliency or spring rate of the
underspring 22 can be varied by changing its thickness or the dimensions of the upper andlower ridges lower ridges 26, defined as W3 in Figure-3, has a marked effect on the stiffness and will generally outwardly converge at least slightly in order better to accommodate the hydrodynamic pressure forces which increase radially. Additionally, as shown in Figure 2,slots upper ridges 24 to divide the upper ridges into three separate sections. With the radially divergingupper ridges 24 divided into three separate sections, the stiffness of the upper ridges will more closely conform to the radially increasing hydrodynamic pressure forces. - The foil thrust bearing of the present invention is shown further enlarged in Figure 5 (static condition) and Figure 6 (dynamic condition). For purposes of better illustrating the invention, the size of the
underspring 22 has been enlarged considerably, more particularly in the axial direction, than the thrust bearingdisk 14. It is important, however, to stress the relative position of thedisk 14 and itsfoils 16 with respect to the upper andlower ridges underspring 22 and in particular the interaction therebetween in the dynamic condition of Figure 6. - In the static or non-operating condition of Figure 5, the
foils 16 of the thrust bearingdisk 14 are shown as having theupper ridges 24 of theunderspring 22 generally under the trailing edge half thereof. In this static condition neither thedisk 14 nor theunderspring 22 will be deflected and both will be substantially transverse to the eventual axis of rotation. The arrow provided on thethrust runner 10 indicates the direction of rotational movement that the runner will take with respect to thefoils 16 on thedisk 14. In order to assist the establishment of the hydrodynamic film between thefoils 16 and thethrust runner 10, thefoils 16 may be curved as shown in Figure 5 or the leading edge of the foils may be tapered to a thinner thickness than the rest of the foil. - Once relative rotational movement is established between the
thrust runner 10 andthrust plate 28, a hydrodynamic fluid film is developed between thethrust disk foils 16 and the'thrustrunner 10 and the dynamic condition illustrated in Figure 6 will occur. The fluid film pressure gradient established above anindividual foil 16 is generally shown by the varying length of arrows provided above the leftmost foil of Figure 6. This pressure is least at the leading edge of the foil and gradually increases overthe converging orwedge portion of the foil before the position of theupper ridge 24 of theunderspring 22 therebeneath. The maximum pressure occurs in that portion of the foil directly over theupper ridge 24 and then markedly declines to zero near the trailing edge of the foil. - While the dynamic operation of the foil thrust bearing will deform the thrust bearing disk and foils as generally shown in Figure 6, the pressure developed therein will also deflect the
underspring 22 as likewise illustrated in Figure 6. The position of theunderspring 22 above thelower ridges 26 will not change, but the distance between theunderspring 22 above thelower ridges 26 and the underspring side of thedisk 14, defined as d1, will generally be 0.00254 cm to 0.0127 cm less than t, while still providing suitable operation of the thrust bearing. - In addition, under dynamic conditions, the
underspring 22 beneath theupper ridges 24 will be deflected towards the thrust plate 28 a distance defined as d2, such that the spacing between thedisk 22 and thethrust plate 28 in this region will be less than the height of the lower ridges t2. This spacing, t2-d2 depends on the bearing stiffness and hydrodynamic film pressure. - With t1 at least 0.0127 cm greater than t2, even if d2 approaches or actually equals t2 (bottoms out), the
upper ridges 24 will still provide support for thethrust disk 14 so that the hydrodynamic forces will conform the foils to the shape generally shown in Figure 6. Ift1 were to be equal to t2, and d2 equal to t,, then the top of theupper ridges 24 would then be no higher than the upper surface of theunderspring 22 and thefoils 16 would no longer be deflected to form the pressure forming surface as shown.
Claims (11)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US67298284A | 1984-11-19 | 1984-11-19 | |
US672982 | 1984-11-19 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0182535A1 EP0182535A1 (en) | 1986-05-28 |
EP0182535B1 true EP0182535B1 (en) | 1989-01-25 |
Family
ID=24700829
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19850308023 Expired EP0182535B1 (en) | 1984-11-19 | 1985-11-05 | Thrust bearings |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0182535B1 (en) |
DE (1) | DE3567943D1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63158316A (en) * | 1986-12-19 | 1988-07-01 | Daido Metal Kogyo Kk | Thrust bearing |
GB2230305A (en) * | 1989-04-05 | 1990-10-17 | Vickers Plc | Thrust bearing. |
US6354741B1 (en) * | 1999-01-22 | 2002-03-12 | Alliedsignal Inc. | Foil thrust bearing |
JP7070714B2 (en) | 2018-12-25 | 2022-05-18 | 株式会社Ihi | Manufacturing method of thrust foil bearing and base plate of thrust foil bearing |
KR102289217B1 (en) * | 2021-03-31 | 2021-08-13 | 주식회사 뉴로스 | Air foil thrust bearing |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1039434A (en) * | 1965-03-16 | 1966-08-17 | Schmidt Gmbh Karl | Hydrodynamic thrust bearing for journals |
GB1392245A (en) * | 1971-11-12 | 1975-04-30 | Schwermasch Liebknecht Veb K | Axial sliding bearings |
DE2909973C2 (en) * | 1979-03-14 | 1982-10-21 | Forschungsvereinigung Verbrennungskraftmaschinen E.V., 6000 Frankfurt | Aerodynamic springy multi-slide surface bearing |
-
1985
- 1985-11-05 DE DE8585308023T patent/DE3567943D1/en not_active Expired
- 1985-11-05 EP EP19850308023 patent/EP0182535B1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
EP0182535A1 (en) | 1986-05-28 |
DE3567943D1 (en) | 1989-03-02 |
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